A police officer pulls you over on the way home from a friend's house. You drifted over the center line, he says. He wants to give you a breath test to see if you're under the influence.
You're skeptical right away. It's one in the morning, and you're not even sure you drifted over the line. Was the officer just looking for excuses to pull anyone over and check one's blood alcohol concentration (BAC) because it's more likely that drunk drivers are out at night?